Four parameters for the design of cooling water circuit for wheel hub molds

Four parameters for the design of cooling water circuit for wheel hub molds
The design of waterways depends on four parameters: spacing, distance from the cavity, flow rate, and circuit division. Only by coordinating these four parameters can the surface temperature difference of the cavity be compressed to within 15 ℃.
Distance determines temperature uniformity
The distance between waterways is generally between 30-50mm. When the distance is too large, temperature peaks will appear on the surface of the cavity between the two pipes, becoming local hot spots.
Thin walled wheels can be taken as 30-35mm, while thick walled spokes can be relaxed to 45-50mm. The spacing should be set according to the wall thickness zones.
When the spacing is less than 25mm, the processing difficulty and cost increase, and the rigidity of the back of the cavity decreases, requiring an assessment of deformation risk.
The distance from the surface of the cavity is the most sensitive
The distance from the center of the waterway to the surface of the mold cavity is recommended to be no less than 25mm. If it is less than 20mm, local cooling may be too strong, which can easily form a cold insulation.
If the distance is too large, the heat transfer efficiency will decrease and the cooling time will be prolonged. Over 40mm, the water cooling effect is close to that of air cooling.
This distance should vary in different parts of the mold. The hot spot should be closer, while the thin wall should be farther away.
Flow rate is more important than pipe diameter
The common single loop flow rate is 8-20L/min. Insufficient flow, with a temperature difference of over 5 ℃ between inlet and outlet water, indicates insufficient heat transfer capacity.
Controlling the temperature difference between inlet and outlet water within 3-5 ℃ is a reasonable range. If the temperature difference exceeds 8 ℃, it is necessary to increase the flow rate or increase the circuit.
The flow meter should be installed on the mold, rather than estimated based on the machine table. Only by splitting the flow data can the problem circuit be located.
The circuit division should correspond to the hot section
The hot joints in the wheel rim, spokes, and center of the wheel hub are different, and the circuits should be separated. Mixed together, unable to adjust independently.
Wheels larger than 20 inches typically require 8-12 sets of circuits. Too many circuits will increase the number of joints and the risk of water leakage, which needs to be balanced.
In the waterway design of the wheel hub mold, Xinfeng Mold will label the circuit number corresponding to the position of the hot joint for easy on-site debugging by zone.
Conflict between waterways and structures
Waterways should avoid creating injury holes, top rod holes, and exhaust channels. When the distance is less than 8mm, it is prone to water leakage or cracking after long-term use.
The reinforcing ribs on the back of the cavity will block the water path. When designing, it is necessary to consider both the structure and the waterway simultaneously, and not draw each one separately.
The waterway for casting molds is mostly processed by drilling, with straight holes being the main method. Suixing waterway relies on additive manufacturing, which is costly and currently mostly used for small batch high-end molds.
Scaling and maintenance
When the water hardness is high, the inner wall of the waterway will scale. If the scale layer is 1mm, the heat transfer efficiency may decrease by 10% -15%.
The cleaning cycle is usually 12 months, and it should be advanced to 6-8 months when the water quality is too hard. After washing, rinse with clean water until neutral.
During the shutdown period, the waterway should be emptied to avoid water accumulation and corrosion. Long term disuse of molds can cause corrosion on the inner wall, which can block the small aperture circuit.
Feasibility of Waterway Renovation
The old mold has insufficient water channels, and a water jacket can be installed on the back of the mold frame to increase the heat exchange area. The renovation cost is about 15% -20% of the new mold.
Installing a water jacket will change the height of the mold, and the stroke of the press plate on the machine needs to be rechecked. When the height increases by more than 30mm, it may be necessary to replace the transition plate.
Frequently Asked Questions
Question: What is the distance between waterways?
Answer: Usually take 30-50mm, and take the smaller value for thin-walled areas.
Question: How far is it from the surface of the cavity?
Answer: It is recommended to not be less than 25mm, as temperatures below 20mm may cause cold insulation.
Question: How much traffic is appropriate?
Answer: Single loop 8-20L/min, inlet and outlet water temperature difference of 3-5 ℃.
Q: How many sets of circuits are needed?
Answer: 8-12 sets are often required for sizes over 20 inches.
Q: How long does it take to clean the waterway?
Answer: Normally, it takes one year, but if the water quality is hard, it takes about six months.
Question: Is the flexible waterway worth doing?
Answer: High cost, mostly used for small batch high-end molds.
Recommended search keywords
Mold cooling waterway design, hub mold waterway, how to determine waterway spacing, mold flow control, hub mold manufacturer, low-pressure casting mold customization, mold thermal balance, water-cooled mold, waterway scaling cleaning, casting mold manufacturer